The present invention relates to a method for transmitting location-related information between a navigational device, which contains a first location database in which location coordinate pairs and descriptors are assigned to the location specifications, and a receiver for digitally coded traffic messages, the receiver containing a second location database, the present invention also relating to a receiver, suited for carrying out the method, and a navigational device.
In motor vehicles, electronic devices providing the driver with information are in increasing use. In order to guide the driver to a selected destination, navigational devices have become known in which, on the basis of a digital street map and sensors for determining the specific location of the vehicle, for example satellite navigational devices, the most favorable possible route to the destination is calculated and corresponding information is given to the driver. In this context, the so-called digital street map is stored in a location databasexe2x80x94hereinafter also called the map databasexe2x80x94in which the locations necessary for navigation are stored along with their geographic coordinates.
For informing the driver regarding traffic hindrances, various traffic radio-communication systems are known. In this category is the TMC system, in which digitally coded traffic messages are generated on the transmitter side and are decoded in receivers. Details in this regard are described in European Patent No. 0 263 332, German Patent No. 38 10 177, and German Patent No. 38 10 179.
For decoding these digitally coded traffic messages, the receiver must have at least one location database, in which selected locations are listed, classified according to street, for example connecting locations (connections) and intersections.
However, the navigational devices of different manufacturers have different data formats and referencing systems within the map database. As a result, no exchange of information regarding a specific location is possible between different systems. To make navigational devices to some extent compatible with each other and able to be addressed by a service provider that actualizes the map databases, work is currently proceeding on a project of the European Commissionxe2x80x94called EVIDENCExe2x80x94in which an ILOC method (ILOC=Intersection Location) is proposed. However, these suggestions do not result in the known navigational devices being able to take into account digitally coded traffic messages without manual inputs.
Therefore, an object of the present invention is to make possible the exchange of location-related information between a navigational device and a receiver for digitally coded traffic messages.
This object is achieved through the fact
that, in addition to descriptors, location coordinate pairs are stored in the location specifications contained in the second location database,
that along with the information to be transmitted, at least the coordinate pair is transmitted of the location to which the information relates, and
that with the assistance of at least the transmitted coordinate pair, the location specification is selected from the respective location database.
As a result of the method according to the present invention, received digital traffic messages can be transmitted from the receiver to a navigational device, so that, for example, route suggestions determined by the navigational device can automatically be changed in accordance with any traffic disturbances that arise, or traffic messages having previously arrived and been stored are taken into account for a recalculation of a travel route.
The method according to the present invention can also function to transmit information from a navigational device to a receiver for digitally coded traffic messages, for example, on the basis of the coordinates, the appropriate location in the table in the TMC system can be found by approximation and comparison of the descriptors, and the method can be used in a receiver for digital traffic messagesxe2x80x94hereinafter also known as a TMC receiverxe2x80x94to create a message and to communicate it to the user using language. In addition, the specific position can be fed from the navigational device to the TMC receiver, in order to be used in making a selection from the received traffic messages.
Even if the coordinate pairs are formed according to the same standard, for example WGS84, slight variations are possible due to their different sources. In addition, the locations are differently defined in the TMC system and in the navigational devices. Therefore, in refining the method according to the present invention, provision is made that, for purposes of selection, coordinate pairs of the respective location database are used that lie within a tolerance range of the transmitted coordinate pairs.
Specifying the coordinate pair is not determinative for all locations. Thus, for example, locations situated in different planes, i.e., those on and under a bridge, have the same coordinate pair but must be distinguished in the specific system. To exclude errors, in a further refinement of the method according to the present invention, provision is made that, along with the information, descriptors are transmitted that are compared with similar descriptors presumably present in the respective location database. In particular, the transmitted descriptors can be street numbers and/or junction numbers.
Traffic messages that are not highway-related cannot always have a clear location specification assigned to them. In this case, a so-called LLOC (Link Location) is created, the transmitted descriptors being the end points of a street segment.
Advantageous embodiments of the method according to the present invention arise from the fact that information is received from the receiver and is transmitted to the navigational device, or that the information is transmitted from the navigational device to the receiver for digitally coded traffic messages.
The object according to the present invention is achieved in a receiver for digitally coded traffic messages by a device for transmitting location-related information between a navigational device, which contains a first location database in which location coordinate pairs and descriptors are assigned to location specifications, and the receiver, which contains a second location database, location coordinate pairs, in addition to descriptors, being stored in the location specifications contained in the second location database, and, along with the information to be transmitted, it being possible to transmit at least the coordinate pair of the location to which the information relates, making it possible to select the location specification from the given location database.
A navigational device according to the present invention, containing a first location database in which location coordinate pairs and descriptors are assigned to the location specifications, is embodied as a device for transmitting location-related information between the navigational device and a receiver for digitally coded traffic messages, the receiver containing a second location database, in which, in addition to descriptors, location coordinate pairs are stored in the location specifications contained there, and, along with the information to be transmitted, it being possible to transmit at least the coordinate pair of the location to which the information relates, making it possible to select the location specification from the given location database.